Synthetic Wavelength Imaging

Here, we tackle the problem of seeing through scatter with our Synthetic Wavelength Imaging (SWI) approaches - an ensemble of techniques that leverage the information encoded in the beat frequency between two coherent optical fields at closely spaced wavelengths to image through scatter. Our approaches probe the scene at two (or more) closely spaced optical wavelengths and computationally assemble a complex “synthetic field” at a “synthetic wavelength,” which is used for further processing. As the synthetic wavelength is the beat wavelength of the two used optical “carrier” wavelengths, it is freely tunable and can be picked orders of magnitudes larger, so that the computationally assembled synthetic field becomes immune to scatter. Moreover, the fact that “optical” light (e.g., in the VIS or NIR) is still the carrier or the information allows us to use of off-the shelf detector technology such as CMOS cameras. As the synthetic wavelength depends solely on the difference between the two used optical “carrier” wavelengths, the same synthetic wavelength can be realized for different carrier wavelengths pairs in different wavebands best suited for specific tasks (e.g., minimizing absorption).

Besides the various SWI-based approached to image through scattering environments discussed below, our group has harnessed SWI as “high precision Time-of-Flight imaging” method to recover 3D profiles of optically rough surfaces in industrial inspection and computer vision applications (please see ”High-Precision Time-of-Flight Sensing with Synthetic Waves” below for more information).